Field of the Invention
The invention relates to a bus system, in particular in a motor vehicle, which includes a plurality of interconnected control devices, and in which data transmitted on the bus are evaluated in a central device.
Such a bus system interconnects a plurality of control devices which have to interchange data. In the case of use in a motor vehicle, such control devices are, for example, the controller for an antilock braking system and a traction control system, the engine control, the electronic transmission control, the airbag control and the like.
A bus system which replaces the evermore extensive individual wiring cable harnesses in motor vehicles is known from an article in the Conference Proceedings C205/85, I. Mech. E. 1985, pages 227-230, entitled: Proposal for an Automotive Multiplex Wiring System). In that device, a serial bus interconnects independent control devices (engine management, dashboard computer) and modules which are controlled by a central control. The latter controls all of the information inputs and outputs and additionally carries out special tasks (time output, data storage, signalling). The modules which are distributed over the motor vehicle are an interface between signal inputs (switches, sensors) and signal outputs (driver circuits for lamps, motors and actuators) on one hand and the bus on the other hand. The data transmission is always performed through the central computer.
If one of the control devices requires data which are evaluated over relatively long periods, for example statistically prepared data, it must compute them itself in each case by using individually stored algorithms. That produces a large program requirement in the individual control device, and as a result it frequently happens that statistical functions and processes, for example adaptation processes, cannot be carried out although they would be useful.